Collapse of the world's largest herbivores

Scientific priorities and shepherds' perceptions of ungulate's contributions to people in rewilding landscapes

Nature's contributions to people (NCP) are all the contributions of living nature, both beneficial and detrimental, to the societies' life's quality. Ungulates play this dual role of providers of beneficial and detrimental NCP, as they are responsible of the supply of benefits (e.g. extractive experiences, habitat maintenance) and detriments (e.g. crops damage, traffic collisions). Our aim was to analyze the NCP provided by wild ungulates through examining the scientific priorities and the shepherds' perceptions in peninsular Spain. We reviewed scientific articles of NCP provided by ungulates in Spain and conducted questionnaires regarding NCP to shepherds in farming systems where domestic and wild ungulates cohabit. Then, we compared whether the scientific priorities match with those perceived by shepherds. Both stakeholders highlight more detrimental than beneficial NCP, although there are some mismatches between scientific priorities and shepherds' perceptions. Regarding detrimental NCP, soil alteration, silvicultural damage, human safety or traffic collision were included in scientific literature but not mentioned by shepherds. Contrarywise, shepherds mainly considered grazing competence and damage to animals (i.e. game species and livestock) as important detrimental NCP. Concerning beneficial NCP, whilst hunting was prominent in the publications, shepherds did not conceived it as an important beneficial contribution and considered the regulation of organisms (i.e. scavenging alternative prey) important benefits. These results can have twofold implications. The emphasis on detrimental NCP (studied and perceived) can reinforce the idea that ungulates can threaten humans rather than contribute to societies' wellbeing. The fact that research does not address the interests of shepherds can affect the social tolerance towards ungulates as the damages experienced or perceived by shepherds are not studied. Our results show the relevance of considering local knowledge held by shepherds and their perceptions, something highlighted by the NCP approach.

The megabiota are disproportionately important for biosphere functioning

A prominent signal of the Anthropocene is the extinction and population reduction of the megabiota—the largest animals and plants on the planet. However, we lack a predictive framework for the sensitivity of megabiota during times of rapid global change and how they impact the functioning of ecosystems and the biosphere. Here, we extend metabolic scaling theory and use global simulation models to demonstrate that (i) megabiota are more prone to extinction due to human land use, hunting, and climate change; (ii) loss of megabiota has a negative impact on ecosystem metabolism and functioning; and (iii) their reduction has and will continue to significantly decrease biosphere functioning. Global simulations show that continued loss of large animals alone could lead to a 44%, 18% and 92% reduction in terrestrial heterotrophic biomass, metabolism, and fertility respectively. Our findings suggest that policies that emphasize the promotion of large trees and animals will have disproportionate impact on biodiversity, ecosystem processes, and climate mitigation.

Human-driven losses of megafauna and megaflora may have disproportionate ecological consequences. Here, the authors combine metabolic scaling theory and global simulation models to show that past and continued reduction of megabiota have and will continue to decrease ecosystem and biosphere functioning.

Trophic rewilding revives biotic resistance to shrub invasion

Trophic rewilding seeks to rehabilitate degraded ecosystems by repopulating them with large animals, thereby re-establishing strong top-down interactions. Yet there are very few tests of whether such initiatives can restore ecosystem structure and functions, and on what timescales. Here we show that war-induced collapse of large-mammal populations in Mozambique's Gorongosa National Park exacerbated woody encroachment by the invasive shrub Mimosa pigra-considered one of the world's 100 worst invasive species-and that one decade of concerted trophic rewilding restored this invasion to pre-war baseline levels. Mimosa occurrence increased between 1972 and 2015, a period encompassing the near extirpation of large herbivores during the Mozambican Civil War. From 2015 to 2019, mimosa abundance declined as ungulate biomass recovered. DNA metabarcoding revealed that ruminant herbivores fed heavily on mimosa, and experimental exclosures confirmed the causal role of mammalian herbivory in containing shrub encroachment. Our results provide mechanistic evidence that trophic rewilding has rapidly revived a key ecosystem function (biotic resistance to a notorious woody invader), underscoring the potential for restoring ecological health in degraded protected areas.

Modelling the abundance and productivity distribution to understand the habitat–species relationship: the guanaco (Lama guanicoe) case study

Abstract ContextThe conservation of large wild herbivores presents a challenge posed by the fact that their broad habitat requirements overlap with various human activities. Elucidating the factors that explain their distribution patterns provides us with a better understanding of habitat–species relationships and facilitates the design of effective management policies. AimsIdentify the natural (forage availability, weather) and anthropogenic (hunting, interspecific competition) factors that explain the abundance and productivity distribution of the guanaco. Estimate guanaco abundance and productivity and describe their distribution. MethodsWe estimated the abundance and productivity of guanaco by using aerial surveys during the breeding and non-breeding season of two consecutive years, following the strip-transect methodology; we then modelled these as a function of environmental factors by means of density surface models. Key resultsThe highest abundance and productivity of guanaco occurred mostly where mesic grassland was dominant. Guanaco abundance presented three hotspots on the basis of geographic location, and family groups were more productive at low to intermediate livestock level. Abundance was significantly higher in the breeding season for both years (5614 and 14092 individuals) than in the non-breeding season (2922 and 6926 individuals), and it was higher in 2015 than in 2014. Productivity was higher in 2015 than in 2014 (0.54 and 0.46 calves per adult respectively). ConclusionsGuanaco responded to forage availability, occupying zones with low to intermediate food availability in the breeding season, and those with the highest availability in the non-breeding season. This could be due to interspecific competition between livestock and guanaco family groups. We propose that the overall guanaco response could also be explained by social structure or by unassessed factors such as predation risk by feral dogs. ImplicationsThe guanaco could compensate for the use of habitats with a lower food availability during the breeding season by using better-quality habitats during the non-breeding season.

Trophic Rewilding Advancement in Anthropogenically Impacted Landscapes (TRAAIL): A framework to link conventional conservation management and rewilding

A variety of rewilding initiatives are being implemented across Europe, generally characterized by a more functionalist approach to nature management compared to the classic compositional approach. To address the increasing need for a framework to support implementation of rewilding in practical management, we present TRAAIL-Trophic Rewilding Advancement in Anthropogenically Impacted Landscapes. TRAAIL has been co-produced with managers and other stakeholders and provides managers with a framework to categorize rewilding initiatives and to link conventional nature management and rewilding by guiding steps towards a higher degree of self-regulation. Applying TRAAIL to data obtained in a Danish survey of rewilding-inspired initiatives we find that out of 44 initiatives there is no "Full rewilding" initiatives, 3 "Near-full rewilding" initiatives, 23 "Partial rewilding" initiatives, 2 "minimal rewilding" initiatives and 16 "Effort-intensive conservation management" initiatives. This study shows how TRAAIL can guide and inform trophic rewilding on a local and national scale.

Global change biology: A primer

Because of human action, the Earth has entered an era where profound changes in the global environment are creating novel conditions that will be discernable far into the future. One consequence may be a large reduction of the Earth's biodiversity, potentially representing a sixth mass extinction. With effective stewardship, the global change drivers that threaten the Earth's biota could be alleviated, but this requires clear understanding of the drivers, their interactions, and how they impact ecological communities. This review identifies 10 anthropogenic global change drivers and discusses how six of the drivers (atmospheric CO₂ enrichment, climate change, land transformation, species exploitation, exotic species invasions, eutrophication) impact Earth's biodiversity. Driver impacts on a particular species could be positive or negative. In either case, they initiate secondary responses that cascade along ecological lines of connection and in doing so magnify the initial impact. The unique nature of the threat to the Earth's biodiversity is not simply due to the magnitude of each driver, but due to the speed of change, the novelty of the drivers, and their interactions. Emphasizing one driver, notably climate change, is problematic because the other global change drivers also degrade biodiversity and together threaten the stability of the biosphere. As the main academic journal addressing global change effects on living systems, GCB is well positioned to provide leadership in solving the global change challenge. If humanity cannot meet the challenge, then GCB is positioned to serve as a leading chronicle of the sixth mass extinction to occur on planet Earth.

Browsing and fire decreases dominance of a resprouting shrub in woody encroached grassland

North American grasslands have experienced increased relative abundance of shrubs and trees over the last 150 yr. Alterations in herbivore composition, abundance, and grazing pressure along with changes in fire frequency are drivers that can regulate the transition from grassland to shrubland or woodland (a process known as woody encroachment). Historically, North American grasslands had a suite of large herbivores that grazed and/or browsed (i.e., bison, elk, pronghorn, deer), as well as frequent and intense fires. In the tallgrass prairie, many large native ungulates were extirpated by the 1860s, corresponding with increased homesteading (which led to decreased fire frequencies and intensities). Changes in the frequency and intensity of these two drivers (browsing and fire) have coincided with woody encroachment in tallgrass prairie. Within tallgrass prairie, woody encroachment can be categorized in to two groups: non-resprouting species that can be killed with fire and resprouting species that cannot be killed with fire. Resprouting species require additional active management strategies to decrease abundance and eventually be removed from the ecosystem. In this study, we investigated plant cover, ramet density, and physiological effects of continuous simulated browsing and prescribed fire on Cornus drummondii C.A. Mey, a resprouting clonal native shrub species. Browsing reduced C. drummondii canopy cover and increased grass cover. We also observed decreased ramet density, which allowed for more infilling of grasses. Photosynthetic rates between browsed and unbrowsed control shrubs did not increase in 2015 or 2016. In 2017, photosynthetic rates for browsed shrubs were higher in the unburned site than the unbrowsed control shrubs at the end of the growing season. Additionally, after the prescribed fire, browsed shrubs had ~90% decreased cover, ~50% reduced ramet density, and grass cover increased by ~80%. In the roots of browsed shrubs after the prescribed fire, nonstructural carbohydrates (NSC) experienced a twofold reduction in glucose and a threefold reduction in both sucrose and starch. The combined effects of browsing and fire show strong potential as a successful management tool to decrease the abundance of clonal-resprouting woody plants in mesic grasslands and illustrate the potential significance of browsers as a key driver in this ecosystem.

The landscape-scale drivers of herbivore assemblage distribution on the central basalt plains of Kruger National Park

The distribution and abundance of herbivores in African savannas are constrained by interactions between abiotic and biotic factors. At the species-level, herbivores face trade-offs among foraging requirements, vegetation structure and the availability of surface water that change over spatial and temporal scales. Characterizing herbivore requirements is necessary for the management of the environment in which they occur, as conservation management interventions such as fencing and artificial water provision consequently have effects on how herbivores address these trade-offs. We tested the effects of environmental attributes on the probability of presence of herbivore functional types at different distances to water in the Satara section of Kruger National Park over the period of a year. Hypotheses about species’ relative distribution and abundance were developed through a literature review of forage and water availability constraints on feeding preference and body size of herbivore. We expected strong seasonal relationships between vegetation biomass and quality, and biomass of water-dependent herbivores with increasing distance to water. Our analyses of herbivore distribution across the region confirmed broad-scale descriptions of interactions between forage requirements and water availability across a set of species which differ in functional traits.

Geographically divergent evolutionary and ecological legacies shape mammal biodiversity in the global tropics and subtropics

Studies of the factors governing global patterns of biodiversity are key to predicting community responses to ongoing and future abiotic and biotic changes. Although most research has focused on present-day climate, a growing body of evidence indicates that modern ecological communities may be significantly shaped by paleoclimatic change and past anthropogenic factors. However, the generality of this pattern is unknown, as global analyses are lacking. Here we quantify the phylogenetic and functional trait structure of 515 tropical and subtropical large mammal communities and predict their structure from past and present climatic and anthropogenic factors. We find that the effects of Quaternary paleoclimatic change are strongest in the Afrotropics, with communities in the Indomalayan realm showing mixed effects of modern climate and paleoclimate. Malagasy communities are poorly predicted by any single factor, likely due to the atypical history of the island compared with continental regions. Neotropical communities are mainly codetermined by modern climate and prehistoric and historical human impacts. Overall, our results indicate that the factors governing tropical and subtropical mammalian biodiversity are complex, with the importance of past and present factors varying based on the divergent histories of the world's biogeographic realms and their native biotas. Consideration of the evolutionary and ecological legacies of both the recent and ancient past are key to understanding the forces shaping global patterns of present-day biodiversity and its response to ongoing and future abiotic and biotic changes in the 21st century.

Habitat heterogeneity and social factors drive behavioral plasticity in giraffe herd-size dynamics

Behavioral plasticity, or the mechanism by which an organism can adjust its behavior in response to exogenous change, has been highlighted as a potential buffer against extinction risk. Giraffes (Giraffa spp.) are gregarious, long-lived, highly mobile megaherbivores with a large brain size, characteristics that have been associated with high levels of behavioral plasticity. However, while there has been a recent focus on genotypic variability and morphological differences among giraffe populations, there has been relatively little discussion centered on behavioral flexibility within giraffe populations. In large wild herbivores, one measure of behavioral plasticity is the ability to adjust herd size in line with local environmental conditions. Here, we examine whether a genetically isolated population of Angolan giraffes (G. g. angolensis) in a heterogeneous environment adjust their herd sizes in line with spatiotemporal variation in habitat. Our results suggest that ecological factors play a role in driving herd size, but that social factors also shape and stabilize herd-size dynamics. Specifically, we found that 1) mixed-sex herds were larger than single-sex herds, suggesting that sexual composition of herds played a role in driving herd size; 2) the presence of young did not influence herd size, suggesting that giraffes did not make use of the dilution effect to safeguard their young from predation; and 3) there was a strong relationship between herd size and spatial, but not seasonal, variation in food biomass availability, suggesting stability in herd sizes over time, but temporary variation in line with resource availability. These findings indicate that giraffes adjust herd size in line with local exogenous factors, signaling high behavioral plasticity, but also suggest that this mechanism operates within the constraints of the social determinants of giraffe herd size.

Wild Steps in a semi-wild setting? Habitat selection and behavior of European bison reintroduced to an enclosure in an anthropogenic landscape

Recently, several wild or semi-wild herds of European bison have been reintroduced across Europe. It is essential for future successful bison reintroductions to know how the European bison use different habitats, which environmental parameters drive their habitat selection, and whether their habitat use and behavioural patterns in new reintroduction sites differ from habitats where European bison have been roaming freely for a long time. Here, we address these questions for a 40-ha enclosed site that has been inhabited by semi-free ranging European bison since 2012. The site, Vorup Meadows, is adjacent to the Gudenå river in Denmark and consists of human-modified riparian meadows. During 2013 we monitored the behavioural pattern and spatial use of the 11 bison present and in parallel carried out floristic analyses to assess habitat structure and food quality in the enclosure. We tested habitat use and selection against environmental parameters such as habitat characteristics, plant community traits, topography, and management area (release area vs. meadow area) using linear regression and spatial models. The bison herd had comparable diurnal activity patterns as observed in previous studies on free-roaming bison herds. Topography emerged as the main predictor of the frequency of occurrence in our spatial models, with high-lying drier areas being used more. Bison did not prefer open areas over areas with tree cover when accounting for habitat availability. However, they spent significantly more time in the release area, a former agricultural field with supplementary fodder, than expected from availability compared to the rest of the enclosure, a meadow with tree patches. We wish to increase awareness of possible long-term ethological effects of the release site and the management protocols accomplished here that might reduce the ecological impact by the bison in the target habitat, and thereby compromise or even oppose the conservation goals of the conservation efforts.

Do protection gradients explain patterns in herbivore densities? An example with ungulates in Zambia's Luangwa Valley

Ungulate populations face declines across the globe, and populations are commonly conserved by using protected areas. However, assessing the effectiveness of protected areas in conserving ungulate populations has remained difficult. Using herd size data from four years of line transect surveys and distance sampling models, we modeled population densities of four important herbivore species across a gradient of protection on the edge of Zambia's South Luangwa National Park (SLNP) while accounting for the role of various ecological and anthropogenic variables. Our goal was to test whether protection was responsible for density dynamics in this protection gradient, and whether a hunting moratorium impacted herbivore densities during the studies. For all four species, we estimated lower densities in partially protected buffer areas adjacent to SLNP (ranging from 4.5-fold to 13.2-fold lower) compared to protected parklands. Density trends through the study period were species-specific, with some species increasing, decreasing, or remaining stable in all or some regions of the protection gradient. Surprisingly, when controlling for other covariates, we found that these observed differences were not always detectably related to the level of protection or year. Our findings highlight the importance of accounting for variables beyond strata of interest in evaluating the effectiveness of a protected area. This study highlights the importance of comprehensively modeling ungulate population density across protection gradients, identifies lands within an important protection gradient for targeted conservation and monitoring, documents prey depletion and expands our understanding on the drivers in a critical buffer area in Zambia.

Longest terrestrial migrations and movements around the world

Long-distance terrestrial migrations are imperiled globally. We determined both round-trip migration distances (straight-line measurements between migratory end points) and total annual movement (sum of the distances between successive relocations over a year) for a suite of large mammals that had potential for long-distance movements to test which species displayed the longest of both. We found that caribou likely do exhibit the longest terrestrial migrations on the planet, but, over the course of a year, gray wolves move the most. Our results were consistent with the trophic-level based hypothesis that predators would move more than their prey. Herbivores in low productivity environments moved more than herbivores in more productive habitats. We also found that larger members of the same guild moved less than smaller members, supporting the ‘gastro-centric’ hypothesis. A better understanding of migration and movements of large mammals should aid in their conservation by helping delineate conservation area boundaries and determine priority corridors for protection to preserve connectivity. The magnitude of the migrations and movements we documented should also provide guidance on the scale of conservation efforts required and assist conservation planning across agency and even national boundaries.

Breeding Centers, Private Ranches, and Genomics for Creating Sustainable Wildlife Populations

Human-induced changes to environments are causing species declines. Beyond preserving habitat (in situ), insurance (ex situ) populations are essential to prevent species extinctions. The Conservation Centers for Species Survival (C2S2) is leveraging space of breeding centers and private ranches to produce “source populations”—genetically diverse reservoirs that also support research and reintroductions. The initial focus is on four African antelopes. C2S2 has developed a program, the Source Population Alliance, that emphasizes animals living in spacious, naturalistic conditions in greater numbers than can be accommodated by urban zoos. Simulation modeling demonstrates how herds can rapidly increase population abundance and retain genetic diversity. Advances in genomics and resulting DNA data allow monitoring of genetic diversity and parentage as well as refined decision-making. This approach, neither pure in situ nor ex situ, but rather “sorta situ”, is an innovative way of linking public and private sector resources to ensure that endangered species survive.

Early hominins evolved within non-analog ecosystems

Present-day African ecosystems serve as referential models for conceptualizing the environmental context of early hominin evolution, but the degree to which modern ecosystems are representative of those in the past is unclear. A growing body of evidence from eastern Africa's rich and well-dated late Cenozoic fossil record documents communities of large-bodied mammalian herbivores with ecological structures differing dramatically from those of the present day, implying that modern communities may not be suitable analogs for the ancient ecosystems of hominin evolution. To determine when and why the ecological structure of eastern Africa's herbivore faunas came to resemble those of the present, here we analyze functional trait changes in a comprehensive dataset of 305 modern and fossil herbivore communities spanning the last ∼7 Myr. We show that nearly all communities prior to ∼700 ka were functionally non-analog, largely due to a greater richness of non-ruminants and megaherbivores (species >1,000 kg). The emergence of functionally modern communities precedes that of taxonomically modern communities by 100,000s of years, and can be attributed to the combined influence of Plio-Pleistocene C₄ grassland expansion and pulses of aridity after ∼1 Ma. Given the disproportionate ecological impacts of large-bodied herbivores on factors such as vegetation structure, hydrology, and fire regimes, it follows that the vast majority of early hominin evolution transpired in the context of ecosystems that functioned unlike any today. Identifying how past ecosystems differed compositionally and functionally from those today is key to conceptualizing ancient African environments and testing ecological hypotheses of hominin evolution.

Effects of land-use change on community diversity and composition are highly variable among functional groups

In order to understand how the effects of land-use change vary among taxa and environmental contexts, we investigate how three types of land-use change have influenced phylogenetic diversity (PD) and species composition of three functionally distinct communities: plants, small mammals, and large mammals. We found large mammal communities were by far the most heavily impacted by land-use change, with areas of attempted large wildlife exclusion and intense livestock grazing, respectively, containing 164 and 165 million fewer years of evolutionary history than conserved areas (~40% declines). The effects of land-use change on PD varied substantially across taxa, type of land-use change, and, for most groups, also across abiotic conditions. This highlights the need for taxa-specific or multi-taxa evaluations, for managers interested in conserving specific groups or whole communities, respectively. It also suggests that efforts to conserve and restore PD may be most successful if they focus on areas of particular land-use types and abiotic conditions. Importantly, we also describe the substantial species turnover and compositional changes that cannot be detected by alpha diversity metrics, emphasizing that neither PD nor other taxonomic diversity metrics are sufficient proxies for ecological integrity. Finally, our results provide further support for the emerging consensus that conserved landscapes are critical to support intact assemblages of some lineages such as large mammals, but that mosaics of disturbed land-uses, including both agricultural and pastoral land, do provide important habitats for a diverse array of plants and small mammals.

Ecology of a widespread large omnivore, Homo sapiens, and its impacts on ecosystem processes

Discussions of defaunation and taxon substitution have concentrated on megafaunal herbivores and carnivores, but mainly overlooked the particular ecological importance of megafaunal omnivores. In particular, the Homo spp. have been almost completely ignored in this context, despite the extinction of all but one hominin species present since the Plio-Pleistocene. Large omnivores have a particular set of ecological functions reflecting their foraging flexibility and the varied disturbances they create, functions that may maintain ecosystem stability and resilience. Here, we put the ecology of Homo sapiens in the context of comparative interspecific ecological roles and impacts, focusing on the large omnivore guild, as well as comparative intraspecific variation, focusing on hunter-gatherers.We provide an overview of the functional traits of H. sapiens, which can be used to spontaneously provide the functions for currently ecologically extinct or endangered ecosystem processes. We consider the negative impacts of variations in H. sapiens phenotypic strategies, its possible status as an invasive species, and the potential to take advantage of its learning capacities to decouple negative and positive impacts.We provide examples of how practices related to foraging, transhumance, and hunting could contribute to rewilding-inspired programs either drawing on hunter-gatherer baselines of H. sapiens, or as proxies for extinct or threatened large omnivores. We propose that a greater focus on intraspecific ecological variation and interspecific comparative ecology of H. sapiens can provide new avenues for conservation and ecological research.

Effects of human-induced prey depletion on large carnivores in protected areas: Lessons from modeling tiger populations in stylized spatial scenarios

Prey depletion is a major threat to the conservation of large carnivore species globally. However, at the policy-relevant scale of protected areas, we know little about how the spatial distribution of prey depletion affects carnivore space use and population persistence. We developed a spatially explicit, agent-based model to investigate the effects of different human-induced prey depletion experiments on the globally endangered tiger (Panthera tigris) in isolated protected areas-a situation that prevails throughout the tiger's range. Specifically, we generated 120 experiments that varied the spatial extent and intensity of prey depletion across a stylized (circle) landscape (1,000 km2) and Nepal's Chitwan National Park (~1,239 km2). Experiments that created more spatially homogenous prey distributions (i.e., less prey removed per cell but over larger areas) resulted in larger tiger territories and smaller population sizes over time. Counterintuitively, we found that depleting prey along the edge of Chitwan National Park, while decreasing tiger numbers overall, also decreased female competition for those areas, leading to lower rates of female starvation. Overall our results suggest that subtle differences in the spatial distributions of prey densities created by various human activities, such as natural resource-use patterns, urban growth and infrastructure development, or conservation spatial zoning might have unintended, detrimental effects on carnivore populations. Our model is a useful planning tool as it incorporates information on animal behavioral ecology, resource spatial distribution, and the drivers of change to those resources, such as human activities.

Rewilding complex ecosystems

The practice of rewilding has been both promoted and criticized in recent years. Benefits include flexibility to react to environmental change and the promotion of opportunities for society to reconnect with nature. Criticisms include the lack of a clear conceptualization of rewilding, insufficient knowledge about possible outcomes, and the perception that rewilding excludes people from landscapes. Here, we present a framework for rewilding that addresses these concerns. We suggest that rewilding efforts should target trophic complexity, natural disturbances, and dispersal as interacting processes that can improve ecosystem resilience and maintain biodiversity. We propose a structured approach to rewilding projects that includes assessment of the contributions of nature to people and the social-ecological constraints on restoration.

Historical records reveal the distinctive associations of human disturbance and extreme climate change with local extinction of mammals

Human impacts and climatic changes are widely considered to be responsible for rapid species extinction. However, determining their effects is challenging owing to the lack of long-term spatial–temporal data. In this study, we quantified the distinctive associations of anthropogenic and climatic stressors with the local extinction of 11 medium- or large-sized mammals using historical records over the past 3 centuries. We found that the increased local extinction of mammals was associated with intensified human disturbance (particularly for large-sized mammals) and with extreme temperature change (both cooling and warming). Our results provide insight into biodiversity conservation during the Anthropocene.

Accelerated anthropogenic impacts and climatic changes are widely considered to be responsible for unprecedented species extinction. However, determining their effects on extinction is challenging owing to the lack of long-term data with high spatial and temporal resolution. In this study, using historical occurrence records of 11 medium- to large-sized mammal species or groups of species in China from 905 BC to AD 2006, we quantified the distinctive associations of anthropogenic stressors (represented by cropland coverage and human population density) and climatic stressors (represented by air temperature) with the local extinction of these mammals. We found that both intensified human disturbances and extreme climate change were associated with the increased local extinction of the study mammals. In the cold phase (the premodern period of China), climate cooling was positively associated with increased local extinction, while in the warm phase (the modern period) global warming was associated with increased local extinction. Interactive effects between human disturbance and temperature change with the local extinction of elephants, rhinos, pandas, and water deer were found. Large-sized mammals, such as elephants, rhinos, and pandas, showed earlier and larger population declines than small-sized ones. The local extinction sensitivities of these mammals to the human population density and standardized temperature were estimated during 1700 to 2000. The quantitative evidence for anthropogenic and climatic associations with mammalian extinction provided insights into the driving processes of species extinction, which has important implications for biodiversity conservation under accelerating global changes.

Can plant traits predict seed dispersal probability via red deer guts, fur, and hooves?

ABSTRACT

Seed dispersal by mammals provides functional connectivity between isolated plant habitat patches. Across much of Europe, red deer (Cervus elaphus) populations are growing steadily, potentially leading to increasing importance of this large mammal species to plant dispersal. While deer endozoochory is relatively well studied, epizoochory via fur and hoof attachment is much less understood. Seed dispersal internally and externally on 57 red deer individuals was investigated by sampling the seed content of intestinal tracts, fur, and hooves of animals shot during annual hunts in four contrasted landscapes in Denmark. We assessed compositional differences between dispersal modes whether plant species' association to a dispersal mode could be predicted by seed traits, whole-plant traits, and species' local abundance. We found the largest difference in seed species composition to be between epizoochory (fur and hooves) and endozoochory (gut contents). Probability of plant dispersal through guts and fur was correctly predicted from traits more often than not. Hoof-epizoochory, however, could not be correctly predicted from plant traits. Most plant species encountered were picked up by all three dispersal modes, suggesting an overriding effect of plant abundance in the landscapes in which the deer roam, which was also indicated by the statistical analysis. Nonetheless, a significant proportion of species were associated with either gut, fur, or hoof-borne dispersal, reflecting the effect of plant traits and, potentially, animal behavior. Plant species being dispersed more often than expected through intestines were mainly associated with ruderal habitats, whereas species transported via fur tended toward association with wooded habitats. Considering the increasing red deer populations in Europe, and the differences between seed dispersal modes, all modes of animal seed dispersal should be taken into account in future studies.

OPEN RESEARCH BADGES

This article has been awarded Open Data and Open Materials Badges. All materials and data are publicly accessible via the Open Science Framework at https://doi.org/10.6084/m9.figshare.7982483 and https://doi.org/10.6084/m9.figshare.7982483.

Human dimensions of wildlife conservation in Iran: Assessment of human-wildlife conflict in restoring a wide-ranging endangered species

Human-wildlife conflicts restrict conservation efforts, especially for wide-ranging animals whose home ranges overlap with human activities. We conducted a study to understand conflicts with, and factors influencing the perceived value of an expanding population of onagers (Equus hemionus onager) in local communities in southern Iran. We asked about locals’ perceptions of six potential management strategies intended to lessen human-onager conflict. We found that human-onager conflict was restricted to 45% of respondents within the Bahram-e-Goor Protected Area, all of whom were involved in farming or herding activities. Locals within the protected area were more knowledgeable about onagers and valued onagers more than those living outside the protected area. The perceived value of onagers increased with level of education, total annual income, and perceptions of onager population trends; the perceived value of onagers decreased with the magnitude of conflict between onagers and locals. To tolerate or avoid conflicts with onagers, locals were supportive of monetary compensation and changing from a traditional lifestyle to industrialized farming (for farmers) or livestock production (for herders) with the help of government; locals did not support selling land to the government. Our study is among the first in human-wildlife conflict and local attitudes towards an endangered species and its recovery in Iran. We conclude that current levels of human-onager conflict are relatively low and perceived value of onagers is still relatively high. Therefore, wildlife authorities should consider the development of mitigation strategies with local communities before conflicts intensify.

Mammalian tolerance to humans is predicted by body mass: evidence from long-term archives

Humans are implicated as a major driver of species extinctions from the Late Pleistocene to the present. However, our predictive understanding of human-caused extinction remains poor due to the restricted temporal and spatial scales at which this process is typically assessed, and the risks of bias due to "extinction filters" resulting from a poor understanding of past species declines. We develop a novel continent-wide data set containing country-level last-occurrence records for 31 European terrestrial mammals across the Holocene (c.11,500 yr BP to present), an epoch of relative climatic stability that captures major transitions in human demography. We analyze regional extirpations against a high-resolution database of human population density (HPD) estimates to identify species-specific tolerances to changing HPD through the Holocene. Mammalian thresholds to HPD scale strongly with body mass, with larger-bodied mammals experiencing regional population losses at lower HPDs than smaller-bodied mammals. Our analysis enables us to identify levels of tolerance to HPD for different species, and therefore has wide applicability for determining biotic vulnerability to human impacts. This ecological pattern is confirmed across wide spatiotemporal scales, providing insights into the dynamics of prehistoric extinctions and the modern biodiversity crisis, and emphasizing the role of long-term archives in understanding human-caused biodiversity loss.

Large herbivore assemblages in a changing climate: incorporating water dependence and thermoregulation

The coexistence of different species of large herbivores (ungulates) in grasslands and savannas has fascinated ecologists for decades. However, changes in climate, land‐use and trophic structure of ecosystems increasingly jeopardise the persistence of such diverse assemblages. Body size has been used successfully to explain ungulate niche differentiation with regard to food requirements and predation sensitivity. But this single trait axis insufficiently captures interspecific differences in water requirements and thermoregulatory capacity and thus sensitivity to climate change. Here, we develop a two‐dimensional trait space of body size and minimum dung moisture content that characterises the combined food and water requirements of large herbivores. From this, we predict that increased spatial homogeneity in water availability in drylands reduces the number of ungulate species that will coexist. But we also predict that extreme droughts will cause the larger, water‐dependent grazers as wildebeest, zebra and buffalo–dominant species in savanna ecosystems – to be replaced by smaller, less water‐dependent species. Subsequently, we explore how other constraints such as predation risk and thermoregulation are connected to this two‐dimensional framework. Our novel framework integrates multiple simultaneous stressors for herbivores and yields an extensive set of testable hypotheses about the expected changes in large herbivore community composition following climate change.

Walking in Each Other’s Footsteps: Do Animal Trail Makers Confer Resilience against Trampling Tourists?

Modern humans, and other hominins before them, have walked across the landscapes of most continents for many millennia. They shared these landscapes with other large animals, especially mammalian herbivores and their predators, whose footsteps defined trails through the vegetation. Most of the diversity in the wild species is now concentrated in protected areas and visited by large numbers of tourists who may walk amongst them. This review examines the literature about medium-large animal and tourist trampling impacts to uncover any marriage between animal ecology and nature-based tourism research. Methodology is comparable. Animal ecology has focused on the propagation of grazing and trampling effects from a point source (usually water). Tourism research has focused on trail structure (formal/informal, hardened, wide/narrow) and the propagation of effects (especially weeds) into the hinterland and along the trail. There is little research to substantiate an evolutionary view of trampling impacts. At least tourists venturing off formed trails may reduce impacts by following animal trails with caveats, such as risk of encounters with dangerous animals and disruption of animal behavior. This is an under-studied topic but a fertile ground for research, aided by modern tools like trail cameras and geographically enabled devices borne by tourists.

Effects of nutrient supply, herbivory, and host community on fungal endophyte diversity

The microbes contained within free-living organisms can alter host growth, reproduction, and interactions with the environment. In turn, processes occurring at larger scales determine the local biotic and abiotic environment of each host that may affect the diversity and composition of the microbiome community. Here, we examine variation in the diversity and composition of the foliar fungal microbiome in the grass host, Andropogon gerardii, across four mesic prairies in the central United States. Composition of fungal endophyte communities differed among sites and among individuals within a site, but was not consistently affected by experimental manipulation of nutrient supply to hosts (A. gerardii) or herbivore reduction via fencing. In contrast, mean fungal diversity was similar among sites but was limited by total plant biomass at the plot scale. Our work demonstrates that distributed experiments motivated by ecological theory are a powerful tool to unravel the multiscale processes governing microbial community composition and diversity.

Quantifying the dilution effect for models in ecological epidemiology

The dilution effect, where an increase in biodiversity results in a reduction in the prevalence of an infectious disease, has been the subject of speculation and controversy. Conversely, an amplification effect occurs when increased biodiversity is related to an increase in prevalence. We explore the conditions under which these effects arise, using multi species compartmental models that integrate ecological and epidemiological interactions. We introduce three potential metrics for quantifying dilution and amplification, one based on infection prevalence in a focal host species, one based on the size of the infected subpopulation of that species and one based on the basic reproduction number. We introduce our approach in the simplest epidemiological setting with two species, and show that the existence and strength of a dilution effect is influenced strongly by the choices made to describe the system and the metric used to gauge the effect. We show that our method can be generalized to any number of species and to more complicated ecological and epidemiological dynamics. Our method allows a rigorous analysis of ecological systems where dilution effects have been postulated, and contributes to future progress in understanding the phenomenon of dilution in the context of infectious disease dynamics and infection risk.

Whole Genome Sequencing and Re-sequencing of the Sable Antelope (Hippotragus niger): A Resource for Monitoring Diversity in ex Situ and in Situ Populations

Genome-wide assessment of genetic diversity has the potential to increase the ability to understand admixture, inbreeding, kinship and erosion of genetic diversity affecting both captive (ex situ) and wild (in situ) populations of threatened species. The sable antelope (Hippotragus niger), native to the savannah woodlands of sub-Saharan Africa, is a species that is being managed ex situ in both public (zoo) and private (ranch) collections in the United States. Our objective was to develop whole genome sequence resources that will serve as a foundation for characterizing the genetic status of ex situ populations of sable antelope relative to populations in the wild. Here we report the draft genome assembly of a male sable antelope, a member of the subfamily Hippotraginae (Bovidae, Cetartiodactyla, Mammalia). The 2.596 Gb draft genome consists of 136,528 contigs with an N50 of 45.5 Kbp and 16,927 scaffolds with an N50 of 4.59 Mbp. De novo annotation identified 18,828 protein-coding genes and repetitive sequences encompassing 46.97% of the genome. The discovery of single nucleotide variants (SNVs) was assisted by the re-sequencing of seven additional captive and wild individuals, representing two different subspecies, leading to the identification of 1,987,710 bi-allelic SNVs. Assembly of the mitochondrial genomes revealed that each individual was defined by a unique haplotype and these data were used to infer the mitochondrial gene tree relative to other hippotragine species. The sable antelope genome constitutes a valuable resource for assessing genome-wide diversity and evolutionary potential, thereby facilitating long-term conservation of this charismatic species.

Drought-response strategies of savanna herbivores

Climate models predict increases in drought frequency and severity worldwide, with potential impacts on diverse systems, including African savannas. These droughts pose a concern for the conservation of savanna mammal communities, such that understanding how different species respond to drought is vital.Because grass decreases so consistently during droughts, we predict that grass-dependent species (grazers and mixed feeders) will respond strongly to drought, whether by changing diets, seeking drought refugia, or suffering mortality.A recent severe but heterogeneous drought in Kruger National Park, South Africa, afforded a rare opportunity to test these hypotheses in situ-crucial, given the central role of landscape-scale movement as a potential herbivore strategy. We used herbivore dung as a proxy, integrating spatial distributions (dung counts) with diet composition (carbon isotope analysis of dung).As predicted, browsers showed little response to drought. However, mixed feeders switched their diets to incorporate more C3 trees/forbs, but did not move. Meanwhile, grazers and megaherbivores instead moved toward drought refugia. Synthesis and applications: The responses we observed by savanna herbivores are largely amplifications of typical dry season strategies and reflect constraints imposed by body size and feeding ecology. Grazers may be at particular risk from increased drought frequency and spatial extent if drought refugia become decreasingly available. Conservation strategies should recognize these constraints and work to facilitate the diverse responses of herbivores to drought.

Rapid molecular assays for species and sex identification of swamp deer and other coexisting cervids in human-dominated landscapes of the Terai region and upper Gangetic plains, northern India: implications in understanding species distribution and population parameters

Burgeoning pressures of habitat loss is a major cause of herbivore decline across India, forcing them to coexist with humans in non-protected areas. Their conservation in such landscapes is challenging due to paucity of ecological and demographic information. The northern subspecies of swamp deer, Rucervus duvaucelii duvaucelii, is one such herbivore that lives across human dominated landscapes in Terai region and upper Gangetic plains of north India. Here, we describe species-specific molecular markers and a cervid-specific molecular sexing assay for swamp deer and four other coexisting cervids sambar, chital, barking deer and hog deer. Our markers show species-specific band patterns and a high success rate of 88.21% in large number of field collected referencesamples for all species. Faecal pellets from pilot swamp deer survey samples from upper Ganges basin show 93.81% success rate, and only 5.5% misidentification based on morphological characteristics. Our cervid-specific molecular sexing multiplex assay accurately ascertained 81.15% samples to respective sexes. These molecular approaches provide an easy, quick and cheap option to generate critical information on herbivore population parameters and aid their conservation in this mosaic of protected and non-protected grassland habitats.

Projected losses of global mammal and bird ecological strategies

Species, and their ecological strategies, are disappearing. Here we use species traits to quantify the current and projected future ecological strategy diversity for 15,484 land mammals and birds. We reveal an ecological strategy surface, structured by life-history (fast-slow) and body mass (small-large) as one major axis, and diet (invertivore-herbivore) and habitat breadth (generalist-specialist) as the other. We also find that of all possible trait combinations, only 9% are currently realized. Based on species' extinction probabilities, we predict this limited set of viable strategies will shrink further over the next 100 years, shifting the mammal and bird species pool towards small, fast-lived, highly fecund, insect-eating, generalists. In fact, our results show that this projected decline in ecological strategy diversity is much greater than if species were simply lost at random. Thus, halting the disproportionate loss of ecological strategies associated with highly threatened animals represents a key challenge for conservation.

Identifying Shared Strategies and Solutions to the Human–Giant Tortoise Interactions in Santa Cruz, Galapagos: A Nominal Group Technique Application

Conservation conflicts in protected areas are varied and context-specific, but the resulting effects are often similar, leading to important losses for both humans and wildlife. Several methods and approaches have been used to mitigate conservation conflicts, with an increasing emphasis on understanding the human–human dimension of the conflict. In this article, we present a revision of several conservation conflict cases in the management of protected areas, transdisciplinary and participatory approaches to address conservation conflicts, and finalize by illustrating the application of the nominal group technique (NGT) with the case of the human–giant tortoise interactions in Santa Cruz Island, Galapagos. In this article, we demonstrate the use of novel and systematic participatory and deliberative methodology that is able to engage stakeholders in a constructive dialogue to jointly identify and explore options for shared strategies and solutions to conservation conflicts. The results are comparable with other conservation conflicts cases around the world and illustrate the importance of generating legitimatized information that will further help policy and decision-making actions to address conservation conflicts in the management of protected areas.

Long-term changes in northern large-herbivore communities reveal differential rewilding rates in space and time

Herbivores have important impacts on ecological and ecosystem dynamics. Population density and species composition are both important determinants of these impacts. Large herbivore communities are shifting in many parts of the world driven by changes in livestock management and exploitation of wild populations. In this study, we analyse changes in large herbivore community structure over 66 years in Norway, with a focus on the contribution of wildlife and livestock. We calculate metabolic biomass of all large-herbivore species across the whole region between 1949 and 2015. Temporal and spatial patterns in herbivore community change are investigated and we test hypotheses that changes in wildlife biomass are driven by competition with livestock. We find that total herbivore biomass decreased from 1949 to a minimum in 1969 due to decreases in livestock biomass. Increasing wild herbivore populations lead to an increase in total herbivore biomass by 2009. Herbivore communities have thus reverted from a livestock dominated state in 1949 (2% of large herbivore metabolic biomass comprised of wildlife species) to a state with roughly equal wildlife and livestock (48% of metabolic biomass comprised of wildlife species). Declines in livestock biomass were a modest predictor of wildlife increases, suggesting that competition with livestock has not been a major limiting factor of wild herbivore populations over the past decades. Instead there was strong geographic variation in herbivore community change, with milder lowland regions becoming more dominated by wild species, but colder mountain and northern regions remaining dominated by livestock. Our findings indicate that there has been notable rewilding of herbivore communities and herbivore-ecosystem interactions in Norway, particularly in milder lowland regions. However, Norwegian herbivores remain mostly regulated by management, and our findings call for integrated management of wild and domestic herbivores.